Feed mechanism for externally powered automatic gun



May 11, 1965 J. G. ROCHA 3,

FEED MECHANISM FOR EXTERNALLY POWERED AUTOMATIC GUN Filed June 13. 1961 4 Sheets-Sheet 1 IN VEN TOR.

Jul-111E -Rnchu BY jJ/FRGM; a Q

May 11, 1965 J c; ROCHA 3,

FEED MECHANISM FOR EXTERNALLY POWERED AUTOMATIC GUN Filed June 13, 1961 4 Sheets-Sheet 2 wall/1 I,

m m m John [1R0 ch11 -m mn r y 1, 1965 J. G. ROCHA 3,182,555

FEED MECHANISM FOR EXTERNALLY POWERED AUTOMATIC GUN Filed June 13. 1961 4 Sheets-Sheet 3 Elit;

'E ZLL INVENTOR. J 01111 [1H m ch11 ,m/aama ma Mr y 11, 1965 J. G. ROCHA 3,182,555

FEED MECHANISM FOR EXTERNALLY POWERED AUTOMATIC GUN Filed June 13, 196;

4 Sheets-Sheet 4' IN VEN TOR.

Jnhn llRuchu I28 BY a a pa MAQ W-Q United States Patent 3,182,555 FEED MECHANISM FOR EXTERNALLY POWERED AUTOMATIC GUN John G. Rocha, Westiield, Mass, assignor to the United States of America as represented by the Secretary of the Army Filed June 13, 1961, Ser. No. 116,884 9 Claims. (Cl. 89--33) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to motor driven automatic guns of the type wherein each round is chambered during rearward movement of the barrel into firing position and is more particularly directed to means for feeding a belt of linked cartridges into the gun.

As more fully explained in my copending patent application for Motor Driven Automatic Gun, Serial No. 90,147, filed February 17, 1961, it has been found possible to vary the rate of fire of an automatic gun in a predetermined manner if the barrel is longitudinally reciprocated by a revolving drum which is in turn driven by an electric motor having a variable output. In this gun, the barrel is arranged to move forwardly out of firing or battery position and return rearwardly thereto. As a result, feeding of the cartridges into position to be chambered by the returning barrel is limited to the interval during which the breech end of the barrel is spaced from the mating rear wall surface in the interior of the receiver at a distance greater than the overall length of the cartridge. It is, therefore, necessary to provide a more positive and accu rate control of the intermittent feeding movement of the cartridges than heretofore possible with the sprocket devices ordinarily employed in those guns in which the rate of feed is dependent upon the rate at which the firing mechanism is operated.

Accordingly, it is a broad object of this invention to provide a cartridge feed mechanism for an automatic gun of the type in which a longitudinally reciprocable barrel returns to battery position to chamber and fire in turn each of the cartridges in a linked belt.

Another object of this invention resides in the provision of feed mechanism for the aforesaid type of gun wherein the cartridges are intermittently fed into chant-- bering position in direct synchronization with the rate at which the barrel is reciprocated into and out of firing position.

An additional object of this invention is the provision of a cartridge feed mechanism wherein the means for positioning the leading cartridge in coincident axial alignment with the bore of the barrel is also utilized to maintain such alignment during the return movement of the barrel into firing position.

Still another object of the present invention is to provide a cartridge feed mechanism for a gun of the aforesaid type wherein both the reciprocation of the barrel and the feeding of the cartridges is accomplished by the same externally powered drum.

A further object of this invention is to provide the aforesaid cartridge feed mechanism with means for delaying the inactivation of the feed action thereof in response to the cessation of power to the drum until after the lead ing cartridge has been advanced into position to be fired.

A specific object of the present invention resides in the provision of a cartridge feed mechanism of the aforesaid type wherein the feeding, delinking, and ejection movements of the individual cartridges are limited to a single transverse path.

The specific nature of the invention as well as other p CC Patented May 11, 1965 objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a side elevation of an automatic gun incorpo rating the feed mechanism of this invention and showing the parts in firing position;

FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1;

FIG. 3 is a View similar to FIG. 2 but showing the parts in the positions assumed during the feeding stroke;

FIG. 4 is a cross-sectional view taken along line 44 in FIG. 2 with the cartridge belt partially broken away to show the bottom of the feed tray;

FIG. 5 is a cross-sectional fragmentary view taken along line 55 in FIG. 1 and showing the position of the parts during feeding with the feed pawl cam in the retracted position;

FIG. 6 is a view similar to FIG. 5 but showing the feed pawl cam in the elevated position within the feed path of the cartridge belt;

FIG. 7 is a fragmentary view of FIG. 2 showing the manner in which the feed pawl cam serves to tilt the feed pawl out of engagement with the cartridge belt;

FIG. 8 is a view similar to FIG. 7 but showing the feed pawl at the forward end of the feed stroke;

FIG. 9 is an exploded perspective view of the feeding assembly;

FIG. 10 is a perspective view of the spring utilized to actuate the cartridge positioners; and

FIG. 11 is a perspective View of the breech end of the barrel.

As illustrated in FIG. 1, the gun in which the present invention is incorporated includes a receiver 12 having a forwardly opening bore 14 therein for slidably receiving a barrel 16. A hollow cylindrical drum 18 is rotatably secured between front and rear supports 2t and 22 depending from the underside of receiver 12.. The required clockwise rotation of drum 18 is achieved by an electric motor 24 suitably secured to rear drum support 22 and arranged to provide a variable output. If necessary, motor 24 may be replaced by any suitablecranking device which will permit manual rotation of drum 18. Barrel 16 is longitudinally reciprocated out of and into firing position through the engagement between a suitable follower 25 depending therefrom and a continuous cam track 26 helically formed in the exterior periphery of drum 18.

A feedway 28 extends transversely through receiver 12 and is provided with parallel tracks 30 at the rear end thereof for slidable engagement with the annular rim 32 of the cartridges 34 to be fed therethrough. A feed tray 36 is slidably mounted in opposing T-slots 37 formed into the side of receiver 12 and is relcasably retained in place by spring-biased plungers 38. Feed tray 36 serves to continue feedway 28 and, consequently, the required smooth passage of the cartridges 34 into receiver 12 is ensured by suitable cam surfaces 40 disposed in feed tray 36 adjacent the ends of tracks 36.

A cartridge belt holding pawl 42 is pivotally secured to the top of feed tray 36 adjacent the outer end thereof and projects therethrough into the feed path of cartridges 34. A torsion spring 44 normally urges pawl 42 in a counterclockwise direction to prevent retrograde movement of the entire cartridge belt. However, spring 44 is positioned to permit pawl 42 to ride over the top of each cartridge 34 during the feeding movement of the linked belt.

A feed pawl lever 46 is pivotally secured, as shown at 48, to the vertex of a triangular section 50 projecting outwardly of rear drum support 22. The lower end of lever 46 extends along the front face of section St! to terminate in a forwardly extending cylindrical follower 52 adapted to ride in a closed'cam track 54 of nonsymmetrical contour formed into the rear face of drum 18. The upper end of feed pawl lever 46 is arranged to extend into a longitudinal slot 56 in the underside of a feed pawl 58 which is pivotally connected thereto by a pin 60.

As best illustrated in FIG. 9,'feed pawl 58 is bifurcated to form a pair of upwardly projecting lugs 62 having arcuatefront edges 64 thereon of substantially the same contour as the exterior periphery of cartridge 34. The outer end of pawl 58 is formed with a trailing extension "66 terminating in a forwardly projecting cam follower 68. On each side of pawl 58 and below lugs 62, there is provided an outwardly projectingwing portion 70 for" a purpose to be later shown. Feed pawl 58 is arranged to project upwardly through an open end slot 72 extending transversely into the underside of feed tray 36. Slot 72 is of sufficient length to permit feed pawl 58 to advance each leading cartridge 34 into axial alignment with the bore of barrel 16. However, it has been found that 'the unavoidable variation in the tolerances of the mating partsmay affect the critical length of the feed stroke of pawl 58 to such an extent as to prevent the required axial alignment of the leading cartridge 34. Feed pawl lever 46 is, therefore, preferably constructed in two parts 74 and 75. Upper part 74 is provided with a plurality of vertical serrations 76 at the bottom end thereof adapted to engage with mating serrations 78 in the upper end of part 75. Upper part 74 is also provided with a pair of laterally elongated holes 80 located to align with a pair of similarly spaced circular holes 82 in the serrated end of lower part 75. Thus, part 74 can be adjustably secured to part 75 by bolts 84 to ensure the required chambering position of the leading cartridge 34 at the terminal end of the feed stroke of pawl 58.

A spring-biased plunger 85 is slidably mounted in the upperv end of the feed pawl upper part to bear against the underside of feed pawl 58 inwardly of pivot pin 60 therethrough. Thus, feed pawl 58 is normally urged in a clockwise direction to project upwardly through feed tray slot 72 for feeding engagement with the side of a cartridge 34. The upward lift given to pawl 58 is halted by contact of wings 70 with the underside of feed tray 36.

A bracket 86is attached to the underside of feed tray' 36 for supporting a solenoid 87 having a projecting shaft 88 arranged to be actuated along a limited are for a purpose to be shown. The end of bracket 86- adjacent receiver 12 also supports a'substantially rectangular block 90 terminating in a depending end portion 92 having Tsloped converging cam surfaces 102 and 103 while the front face of cam 98 is cut back, as shown at 104, to form a ledge. 106. The front face of cam 98 is also provided with a rectangular groove 108 which slopes downwardly and outwardly to intersect ledge 106. Groove 108 is arranged to slidingly receive a cylindrical stud 110 formed at the upper end of'a follower arm 112 keyed to the free end of solenoid shaft 88 as best shown at 114. Cam 98 is normally urged'in a counterclockwise direction by a spring-biased plunger 116 seated in sloped shelf 94. The upper vertex of cam 98 is thereby biased upwardly through a rectangular slot 118 in the underside of feed tray 36 disposed forwardly of and parallel to slot 72 therein. Ledge 106 is arranged to contact the underside of feed tray 36 to limit the upward projection of feed pawl cam 98 into the feed path of the cartridge belt.

As'best illustrated in FIG. 4, cartridges 34 may be joined by any type of circular link 120 fitted about the exterior periphery thereof and provided on opposite sides with outwardly projecting lugs 122 for slidable engagement with a connector 123 similarly secured to the projecting lugs 122 on the link 120 adjacent thereto. The breech face of barrel 16 is suitably recessed, as best shown at 124 in FIG. 11, to provide transverse passage for the tip of the projectile of cartridge 34 despite slight variations in the required timing relationship between the movement of barrel 16 and that of feed pawl 58. Recesses 124 are additionally slotted to provide mating seats 125 for lugs 122 of link 120 when barrel 16 is in firing position. The rear face 'of barrel 16 is additionally cut away at the top and bottom thereof, as indicated at 127, to provide clearance for tracks 30 in receiver. 12.

A flat spring 126 with a split extendinginto the rear end thereof to form legs 128 and 130 is fixedly secured in the top of receiver 12 immediately above feedway 28. Legs 128 and 130 each overlie a vertical hole 132 communicating with the interior of feedway 28. Cartridge positioners 134 in the form of headed plungers are slidably disposed in holes 132 to extend into feedway 28 into the feed path of rim 32 on'the leading cartridge 34 in the belt. Positioners 134 terminate in V -shaped lower ends forming inner and outer cam surfaces 136 and 138 respectively. As the leading cartridge 34 enters feed tray 36, it lifts the first positioner 134 against the bias of leg 128. Thus, when the periphery of cartridge case rim 32 moves into position to be contacted by inner cam surface 136 on the. foremost positioner 134, the bias imparted to the latter serves to compensate for possible undertravel of the leading cartridge 34 and ensure the proper positioning thereof in coaxial alignment with the bore of barrel16. At the same time, inner cam surface 136 on the second of positioners 134 stops the leading cartridge 34 to prevent overt-ravel thereof. As the caris insufficient. In order to properly accomplish these functions, leg 130 .is preferably of slightlyfgreater width than leg 128.

When gun operation is initiated by the actuation of the trigger (not shown), solenoid 87, which is connected to the source of power (not shown) byleads 140, is also energized to swing shaft 88 and follower arm 112 keyed thereto in a clockwise direction as viewed in FIGS. 5 and 6. The resulting camming movement of stud 110 in groove 108 of feed pawl cam 98 serves to retract the upper vertex portion thereof out of feedway 28' to the inactive position shown in FIGS. 1 and 5 and'is held in such position as long as solenoid 87 is energized. The firing actuation of the trigger will, of course, energize motor 24 to rotate drum 18 in the clockwise direction'and thereby pivot feed pawl lever 46 to advance feed pawl 58 against the leading cartridge 34 in the belt.

Cam track 54 is'provided with a dwell portion 27 so oriented in drum 18 that the feeding movement of :pawl 58 will not begin until the forward end of recesses 124 in the breech face of barrel 16 have'moved beyond the projectile nose of the leading cartridge 34. Thereafter, pawl 58 is advanced to feed the cartridge belt to the position wherein the leading cartridge '34 is' centered between positioners 134 in coaxial alignment with the bore of barrel 16. As feed pawl 58 is advanced, wings 70 thereon ride along the underside of feed tray 36 to maintain the arcuate front ends64 of feed pawl lugs 62 in the proper feeding contact with the body of cartridge 34. In orderto com plete the advance of feed pawl 58 before barrel 16 begins to inclose cartridge 34, the slope of the feed portion of cam track 54 is considerably greater than theslope of ais a mse d the corresponding portion of the cam track 26 utilized to reciprocate barrel 16.

During the rearward travel of barrel 16, lugs 122 are contacted by the front ends of slots 125 in barrel 16 so that the continued movement thereof slides link 120 rearwardly along cartridge 34 to the position of FIG. 4. During this rearward movement of link 120, connector 123 is carried therewith out of engagement with the corresponding lugs 122 on link 120 of the adjacent cartridge 34 in the belt. As barrel 16 moves into firing position, the direction of travel of feed pawl 58 is reversed to return to the position required for subsequent feeding engagement with the next cartridge in the belt. As feed pawl 58 moves away from receiver 12, it is cammed beneath the next adjacent cartridge in the belt and snaps up therebehind under the urging of the spring-biased plunger 85. During this recovery movement of feed pawl 58, the cartridge belt is held against retrograde movement in feed tray 36 by holding pawl 42.

After movement of barrel 16 into firing position, the breech is locked and the chambered cartridge fired in the manner explained in the aforementioned copending patent application. The actuation of feed pawl 58 is then repeated in the same manner as that described above. However, when the trigger is released to inactivate the electrical connection to motor 24, solenoid 87 is also inactivated to free shaft 88 thereon for swinging movement. Spring-biased plunger 116 thereupon urges feed pawl cam 98 upwardly into the position shown in FIG. 6. This lifting movement of feed pawl cam 98 will, of course, be delayed by any cartridge 34 which may be momentarily positioned immediately above the upper vertex thereof at the instant the solenoid is released.

As feed pawl cam 98 is lifted to project into the interior of feed tray 36 and halt the feeding movement of the cartridge belt, the contact between cam surfaces 102 or 103 and follower 63 on feed pawl extension 66 will pivot feed pawl 58 to withdraw lugs 62 thereon from the interior of feed tray 36.

In the event this lifting movement of feed pawl cam 98 occurs during the portion of the feeding cycle wherein follower 68 is disposed above cam surface 103 as, for example, the position shown in FIG. 7, feed pawl 58 will be pivoted below the floor of feed tray 36 since the spring acting on plunger 116 is stronger than the one acting on plunger 85. Thus, as drum 18 continues to rotate under the decelerating momentum imparted thereto by motor 24, the continued advance of feed pawl 58 in the feeding direction will not be converted into feeding movement of the cartridge belt. of drum 18 is of sufiicient extent to complete at least one full firing cycle, the cartridge then in chambered position will be fired thereby ensuring that the reciprocating barrel 16 will not stop with any fully or partially chambered live cartridge in firing position.

This safety feature is also present even though feed pawl 58 has advanced sufficiently in the feeding direction so that follower 63 is disposed above cam surface 102 or even entirely out of contact therewith as shown in FIG. 8. In such case, feed pawl 58 will continue to feed the leading cartridge 34 into the chambered position for discharge thereof. But, when the feeding travel of feed pawl 58 is reversed and lugs 62 thereon are cammed below feedway 28 by contact with the next cartridge in the belt, cam follower 68 on feed pawl extension 66 will ride over the junction of converging cam surfaces 102 and 103. Thus, as feed pawl 58 reaches the end of its return movement and begins to travel in a feeding direction, the pivotal movement imparted thereto by cam surface 103 will prevent engagement with the leading unfired cartridge 34 in the belt.

In the event the supply of cartridges in feed tray 36 is exhausted upon the entry therein of the vertex of feed pawl cam 98 so that no cartridge 34 is present to tilt feed pawl 58, this action will be initiated by cam surface 102.

Consequently, since the overtravel It is, therefore, apparent that the cartridge feeding arrangement described above is perfectly synchronized with the firing mechanism of the gun at any rate of fire which may result from the speed of the operating motor. Furthermore, the feeding mechanism of the present invention is arranged to stop feeding during the overtravel rotation of the drum subsequent to the inactivation of the motor circuit by the trigger. However, inasmuch as the termination of the feeding movement is delayed until the leading unfired cartridge is advanced into position to be fired, the gun is provided with an automatic safety feature which prevents the barrel from halting with an unfired cartridge in the firing position.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In an automatic gun having a longitudinally reciprocal barrel, the combination of an externally powered rotatable drum for actuating the barrel into and out of firing position, means for feeding a belt of linked cartridges into the gun comprising a pivotal feed pawl, lever e means for reciprocating said feed pawl to successively feed each of the cartridges in the belt into firing position relative to the barrel, means for converting continuous roation of said drum to pivotal reciprocation of said feed lever means, and means initiated by the cessation of power to said drum for holding said feed pawl out of feeding engagement with the cartridge belt during the continued pivotal reciprocation imparted to said feed lever means by the rotational deceleration of said drum.

2. The combination defined in claim 1 wherein said feed lever means comprises a two part lever having a releasable connection therebetween, and means for adjusting the alignment between the two parts of said lever to terminate the feed movement of said feed pawl immediately upon the positioning of the leading cartridge in axial alignment with the barrel thereby compensating for any accumulation of dimensional tolerances in the cartridge feed means.

3. In an automatic gun having a receiver, a barrel longitudinally reciprocal in the receiver, and an externally powered drum rotatably secured to the receiver for con- :tinuously actuating the barrel forwardly from and rearwardly toward firing position, means for feeding a belt of linked cartridges into the gun comprising a feed lever pivoted to the receiver, said lever having a pivotal feed pawl at one end and a cam follower at the opposite end thereof, a continuous cam track in the drum engageable with said cam follower for converting continuous rotation of the drum to intermittent pivotal reciprocation of said feed lever and thereby to said feed pawl, means for pivoting said feed pawl out of feeding engagement with the leading cartridge in the belt, means for holding said feed pawl pivot means out of engagement with said feed pawl, and means initiated by the cessation of power to the drum for inactivating said holding means whereby said feed pawl is pivoted below the feed path of the cartridge belt to prevent feeding engagement therewith during the continued pivotal reciprocation imparted to said feed lever by the rotational momentum of the decelerating drum.

4. The combination defined in claim 3 wherein said means for pivoting said feed pawl out of feeding engagement with the leading cartridge comprise a cam member pivotally mounted in a portion of the receiver below the feed path of the cartridge belt, spring means normally urging said cam member upwardly into blocking engage ment with the cartridge belt, and an extension on said feed pawl engageable by said cam member as a consequence of the upward movement thereof, said cam member having juxtaposed cam surfaces for engaging said feed pawl extension in either direction of said feed pawl movement.

5. In an automatic gun having a receiver with a translever pivoted to one of the depending drum supports, said lever having a feed pawl pivoted to the upper end thereof and a follower stud projecting from the opposite end thereof, a continuous cam track eccentrically disposed in one end of said drum and engageable with said follower stud for converting continuous rotation of the drum to intermittent pivotal reciprocation of said feed lever for alternately advancing and retracting said feed pawl, spring means normally urging said feed pawl into feeding engagement with the leading cartridge in the belt, a pivotal feed pawl cam disposed below the feed path of the car- I tridge belt for movement into and out of blocking engagement with the cartridge belt, a spring-biased plunger normally urging said feed pawl cam upwardly into cartridge belt blocking engagement, an extension on said feed pawl engageable with said feed pawl cam when in the cartridge belt blocking position thereof whereby said feed pawl is pivoted below the feed path of the cartridge belt to prevent feeding engagement therewith during the continued pivotal reciprocation imparted to said feed lever by the rotational decelerating momentum of the durm following the cessation of power thereto, and means for holding said feed pawl carn downwardly against the bias of said plunger to prevent interruption of the feed movement of said feed pawl, said holding means arranged to be inactivated by the cessation of power to the drum. 6. The combination defined in claim wherein said feed pawl cam is angula-rly slotted and said holding means 7. In an automatic gun having a receiver with a transverse feedway therethrough, a'feed tray secured to one side of the receiver in axial alignment with the feedway therein, abarrel slidably mounted in the receiver for longitudinal reciprocation forwardly from and rearwardly toward stationary firing position, and an externally powered drum rotatably mounted below the receiver for reciprocat- A ing the barrel, means, for successively feeding each of the leading cartridges in a disintegrating linked belt into position. to be chambered by the barrel in the firing position thereof comprising a pivotal feed pawl, lever means for reciprocating the feed pawl into successive feeding engagement with the leading cartridge in the belt, means for converting continuous rotation of the drum to pivotal reciprocation of. said feed lever means, a pair of tracks in the rear end of the feedway for slidingly receiving the rim of the leading cartridge, resilient means in the receiver for positioning the leading cartridge into axial alignment, with theboreof the barrel, and a cutout portion in'. the breech end of'the barrel arranged to receive the connecting portion between the links on adjacent 3 cartridges as the barrel moves rearwardly into firing position and thereby forces the link on the leading cartridge to disconnect from the link on the cartridge adjacent thereto.

8. The combination defined in claim 7 wherein said cartridge positioning means comprise a first and second plunger slidably disposed in the topiof the feedway to extend into the feed path of the rim on the leading cartridge, each of said plungers terminatingin V-shaped lower endsforming outer and inner cam surfaces, a split unitary spring fixedly secured in the feedway, said spring having a first and second leg in respective contact with said plungers for imparting resilient bias thereto whereby said innercam surface on said first plunger completes the movement of the leading cartridge into firing position in the event of undertravel thereof and said inner cam surface on said second plunger counteracts any overtravel movement of the leading cartridge, said outer cam surface on said second plunger being also arranged to assist in the ejection of the leading cartridge from the feedway after the firing thereof.

9. In an automatic gun having a receiver with a trans verse feedway therethrough, a feed tray secured to one side of the receiver in axial alignment with the feedway therein, a barrel slidably mounted in the receiver for longitudinal reciprocation forwardly from and rearwardly toward stationary firing position, and an externally powered drum rotatably mounted beneath the receiver for reciprocating the barrel, means for feeding a disintegrating belt of linked cartridges into the gun comprising a pivotal feed lever having a cam follower at the lower end thereof, a continuous eccentric cam track in one end of the drum engageable with said cam follower for converting continu-. ous rotation of the drum to intermittent pivotal reciprocation of said feed lever, a bifurcated feed pawl pivotally mounted on the upper end of said feed lever, said pawl having upwardly projecting feed lugs of arcuate contour and. an extension on the opposite end thereof, the feed tray having a slot therein for the passage of said feed. pawl lugs into contact with the side of a cartridge, a pair of wings on opposite sides of said feed pawl engageable with the underside of the feed tray to limit the up-l ward projection of said feed pawl. lugs therethrough during the feeding advance of the feed pawl, a spring-biased plunger interposed between said feed lever andsaid feed pawl for normally urging the latter into feeding engagetension whereby said feed pawl is cammed below the,

feed tray to prevent subsequent feeding engagement thereof with the cartridge belt during the continued pivotal reciprocation imparted to said feed lever by the rotational momentum of the decelerating drum after the cessation of power thereto.

References Cited by the Examiner UNITED STATES PATENTS 2,655,837

5/58 Lyon 89-161 BENJAMIN A. BORCHELT, Primary Examiner. ARTHUR M. HORTON, SAMUEL BOYD, Examiners.

10/53 Johnson 89--33' 

1. IN AN AUTOMATIC GUN HAVING A LONGITUDINALLY RECIPROCAL BARREL, THE COMBINATION OF AN EXTERNALLY POWERED ROTATABLE DRUM FOR ACTUATING THE BARREL INTO AND OUT OF FIRING POSITION, MEANS FOR FEEDING A BELT OF LINKED CARTRIDGES INTO THE GUN COMPRISING A PIVOTAL FEED PAWL, LEVER MEANS FOR RECIPROCATING SAID FEED PAWL TO SUCCESSIVELY FEED EACH OF THE CARTRIDGES IN THE BELT INTO FIRING POSITION RELATIVE TO THE BARREL, MEANS FOR CONVERTING CONTINUOUS ROTATION OF SAID DRUM TO PIVOTAL RECIPROCATION OF SAID FEED LEVER MEANS, AND MEANS INITIATED BY THE CESSATION OF POWER TO SAID DRUM FOR HOLDING SAID FEED PAWL OUT OF FEEDING ENGAGEMENT WITH THE CARTRIDGE BELT DURING THE CONTINUED PIVOTAL RECIPROCATION IMPARTED TO SAID FEED LEVER MEANS BY THE ROTATIONAL DECELERATION OF SAID DRUM. 